<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <style>
        .box {
            position: relative;
            width: 400px;
            border-bottom: 1px solid #ccc;
            margin: 100px auto;
        }

        .box input {
            width: 370px;
            height: 30px;
            border: 0;
            outline: none;
        }

        .box img {
            position: absolute;
            top: 2px;
            right: 2px;
            width: 24px;
        }
    </style>
    </head>

    <body>
        <div class="box">
            <label for="">
                <img src="img/眼睛_闭.png" alt="" id="eye">
            </label>
            <input type="password" name="" id="pwd">
        </div>
        <script>
            // 需求:点击图片，图片 src 变化，表单类型变化。
            let img = document.querySelector('img');
            let input = document.querySelector('input');

            let flag = true;
            img.onclick = function () {
                if (flag) {
                    img.src = "img/eye.png";
                    input.type = "text";
                } else {
                    img.src = "img/眼睛_闭.png";
                    input.type = "password";
                }
                flag = !flag;
            }
        </script>

    </body>

</html>